基于OpenFOAM的旋转弯曲通道内流动的数值模拟

OpenFOAM Based Numerical Simulation of Flow Field in Rotating Curved Duct

离心式叶轮机械的叶轮通道内的流体流动受到旋转效应与曲率影响而产生强烈的二次流现象。二次流是叶轮通道内流动损失的一个原因,对离心叶轮机械的性能产生不利的影响。应用开源CFD软件OpenFOAM对旋转情况下的90°弯曲通道内的不可压缩流体流场进行三维黏性数值模拟。研究了弯曲通道在不同转速下哥氏力与离心力共同作用对主流速度、二次流及压力特性的影响规律。结果表明:与静止通道相比,旋转产生的哥氏力在弯曲管段形成不对称的二次流,使通道内涡结构变得复杂;甚至在较高转速下二次流方向发生反向。

The behavior of fluid flow in a centrifugal turbomachinery impeller is strongly influenced by the centrifugal force caused by the curvature of the impeller passage and the Coriolis force induced by rotation. Consequently,secondary flow is generated by the combined effects of centrifugal and Coriolis forces and it may induce separation of the boundary layers. Therefore,secondary flow gives an adverse impact on the performance of centrifugal turbomachinery. The application of an open-source CFD codes package OpenFOAM to the prediction of the flow field within a rotating 90°bend duct is presented. At the same time,the effects of Coriolis and centrifugal forces on the velocity,pressure and the development of secondary flow are analyzed according to the numerical results. The analysis result shows that the profile of secondary flow becomes asymmetric due to Coriolis force caused by rotation which is different to the static situation and vortex structures within the duct become more complex. In particular,the direction of the secondary flow may be reversed at higher rotational strengths.